v2.3: xdp: set ring sizes based on configured ethtool values (backport of #6826)

[mergify]

This queries the size of the rings using the ioctl equivalent of ethtool -g <iface>.

This is a prerequisite for a follow up PR that will always populate the fill ring to avoid driver bugs.

---

This is an automatic backport of pull request #6826 done by Mergify.

[mergify]

Cherry-pick of 032a100 has failed:

On branch mergify/bp/v2.3/pr-6826
Your branch is up to date with 'origin/v2.3'.

You are currently cherry-picking commit 032a100c6.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   xdp/src/tx_loop.rs

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   xdp/src/device.rs

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[alessandrod]

why backport: this is a prerequisite for #6846

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 52 lines in your changes missing coverage. Please review.

Project coverage is 82.8%. Comparing base (5c77e1e) to head (6feeee7).

Additional details and impacted files

@@            Coverage Diff            @@
##             v2.3    #6835     +/-   ##
=========================================
- Coverage    82.8%    82.8%   -0.1%     
=========================================
  Files         850      850             
  Lines      379646   379684     +38     
=========================================
- Hits       314518   314499     -19     
- Misses      65128    65185     +57     

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